Be very afraid! Microsoft has given somewhere around 300 millions copies of Windows 10 for free. At 50$ a pop, this translates into about 15 billions $ in potential revenue and trust me, Microsoft is extremely eager to recoup all this huge mountain of cash. In order to do this, they need first that everybody moves to Windows 10 and then all applications come from their store. Let's not forget Microsoft told Wall Street analysts how are they going to monetize users for their entire lifetime: Windows as a service, app store, targeted ads based on personal information slurped from their users. Unless Google who have to chase each of their user, if all goes the Microsoft way they will have 1 billion cash cows ready to be milked on a recurrent basis.